class MyWidget(QWidget):
    def __init__(self, parent=None, data=None):
        self.data = data

class MyWindow(QMainWindow):
    def __init__(self, parent=None):
        self.data_structure = Datastructure() # Abritrary mutable data structure
        self.widget1 = MyWidget(self, data=self.datastructure)
        self.widget2 = MyWidget(self, data=self.datastructure)
        ...

    def load_new_data(path):
        self.data_structure = create_new_data_structure_from_file(path)

• Maintain the reference by putting the data structure inside a mutable container (a list for example)
  
• Create a method in Datastructure to clear/copy data from a new instance.. which seems a huge hassle if the data structure is complex, and the new instance already has all the data I need anyway
  
• Create methods in the widgets to update the reference to the new instances. Reflecting the changes down the line could become cumbersome if the widgets have children and so on...
  
• Destroy old widgets and replace with new ones. Again, this should work fine if limited to a few descendants, maybe not if I have to regenerate a big chunk of my interface as a chain reaction